PREFACE. 13 



myself revised these articles as well as I could, in advance of the 

 publication of Andersson's work on the Salicacece in the forthcoming 

 volume of De Candolle's Prodromus, and of the posthumous volume 

 of the late Dr. Boott's Illustration? of Carex. In the latter genus, 

 however, I have been essentially aided by William Boott, Esq., 

 of Boston, and S. T. Olney, Esq., of Providence, who have made 

 the Carices a special study. To render due acknowledgments to 

 the correspondents who have contributed to the value of the Manual 

 by the communication of specimens, notes, and corrections, would 

 require me to enumerate all the cultivators and numerous amateurs 

 of botany in this country. In special instances their names will be 

 found scattered throughout the pages of the work. The necessity 

 of economizing space to the utmost, so as to keep the volume within 

 the dimensions of a manual, alone has debarred me from fuller 

 citations of the names of collectors and of particular stations of rare 

 or local plants. For the same reason I have generally omitted 

 synonymes, except in case of some original or recent changes in 

 nomenclature. 



There is abundant reason, I doubt not, for me to renew the re- 

 quest that those who use this book will kindly furnish information 

 of all corrections or additions that may appear to be necessary, so 

 that it may be made more accurate and complete hereafter, and 

 maintain the high character which it has earned. 



Some explanations are needful in respect to details of typography, 

 reference, and arrangement. 



Geographical Limitation, Distribution, &c. As is stated 

 on the title-page, this work is intended to comprise the plants which 

 grow spontaneously in the United States north of North Carolina 

 and Tennessee and east of the Mississippi. A Flora of the whole 

 national domain, upon a similar plan (the issue of which I may now 

 hope will not be delayed many years longer), would be much too 

 bulky and expensive for the main purpose which this Manual fulfils. 



